Aspects of this disclosure relate to wireless communications systems. In particular, aspects of this disclosure relate to continuity maintenance of a peer-to-peer group session when a member of the peer-to-peer group exits a coverage area.
Wireless communication systems have developed through various generations, including a first-generation analog wireless phone service (1G), a second-generation (2G) digital wireless phone service (including interim 2.5G and 2.75G networks) and third-generation (3G) and fourth-generation (4G) high speed data/Internet-capable wireless services. There are presently many different types of wireless communication systems in use, including Cellular and Personal Communications Service (PCS) systems. Examples of known cellular systems include the cellular Analog Advanced Mobile Phone System (AMPS), and digital cellular systems based on Code Division Multiple Access (CDMA), Frequency Division Multiple Access (FDMA), Time Division Multiple Access (TDMA), the Global System for Mobile access (GSM) variation of TDMA, and newer hybrid digital communication systems using both TDMA and CDMA technologies.
More recently, Long Term Evolution (LTE) has been developed as a wireless communications protocol for wireless communication of high-speed data for mobile phones and other data terminals. LTE is based on GSM, and includes contributions from various GSM-related protocols such as Enhanced Data rates for GSM Evolution (EDGE), and Universal Mobile Telecommunications System (UMTS) protocols such as High-Speed Packet Access (HSPA).
In recent years, usage of direct peer-to-peer (P2P) communications has increased. LTE Direct (LTE-D) is a proposed 3GPP (Release 12) device-to-device (D2D) solution for proximate discovery. LTE-D dispenses with location tracking and network calls by directly monitoring for services on other LTE-D devices within a large range (˜500 m, line of sight). It does so continuously in a synchronous system that is battery efficient, and can concurrently detect thousands of services in proximity.
LTE-D operates on licensed spectrum as a service to mobile applications. LTE-D enables service layer discovery. Mobile applications on LTE-D devices can instruct LTE-D to set a monitor for mobile application services on other devices. Moreover, mobile applications on LTE-D devices can announce their own services for detection by other LTE-D devices at the physical layer. The applications can be closed while LTE-D works continuously, and notifies the client application when it detects a match to the set monitor.
LTE-D is thus an attractive alternative to mobile developers seeking to deploy proximate discovery solutions as extensions of their existing cloud services. LTE-D is a distributed discovery solution (versus the centralized discovery that exists today), whereby mobile applications forego centralized database processing in identifying relevancy matches, instead autonomously determining relevance at the device level by transmitting and monitoring for relevant attributes. LTE-D offers certain benefits in terms of privacy as well as power consumption, in that LTE-D does not utilize perpetual location tracking to determine proximity. By keeping discovery on the device rather than in the cloud, the user has more control of what information is shared with external devices.
The LTE wireless communications protocol enables LTE-D devices to discover one another, join an LTE-D group, and establish D2D direct data traffic connections among the members of the LTE-D group by configuring LTE-D parameters. For example, the LTE network may configure an interval at which LTE-D devices announce themselves, allocate channel resources for LTE-D sessions, etc. As a result, a problem arises when an LTE-D device performing LTE-D group communications leaves the radio access area of the LTE network. Solutions are needed for seamless continuation of communications among members of an LTE-D group when one of the members exits the radio access area of the LTE network.